1. Field of the Invention
The present invention relates to an object, a method, or a manufacturing method. In addition, the present invention relates to a process, a machine, manufacture, or a composition of matter. One embodiment of the present invention relates to a semiconductor device, a display device, a light-emitting device, a power storage device, a memory device, a driving method thereof, or a manufacturing method thereof. In particular, one embodiment of the present invention relates to a semiconductor device, a memory device, a power supply circuit, a display device, and a light-emitting device each including an oxide semiconductor.
In this specification and the like, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics. In some cases, a display device, an electro-optical device, a semiconductor circuit, or an electronic device includes a semiconductor device.
2. Description of the Related Art
A technique by which a transistor is formed using a semiconductor material has been attracting attention. The transistor is used in a wide range of electronic devices such as an integrated circuit (IC) or an image display device (also simply referred to as a display device). A silicon-based semiconductor material is widely known as a semiconductor material applicable to the transistor, but an oxide semiconductor (OS) has been attracting attention as an alternative material. A transistor in which an oxide semiconductor is used in a channel is referred to as an OS transistor.
For example, a technique for manufacturing a transistor using zinc oxide or an In—Ga—Zn-based oxide semiconductor as an oxide semiconductor applicable to the OS transistor is disclosed (see Patent Documents 1 and 2).
In addition, it has been reported that in the case where a Corbino TFT in which a drain electrode concentrically surrounds a source electrode is formed using an oxide semiconductor, favorable saturation characteristics where the drain voltage of the transistor is constant in a saturation region of Vd−Id (drain voltage−drain current) characteristics can be obtained (Non-Patent Document 1).